In an embodiment, a transistor device includes a semiconductor substrate having a main surface, a cell field including a plurality of transistor cells, and an edge termination region laterally surrounding the cell field. The cell field includes a gate trench in the main surface of the semiconductor substrate, a gate dielectric lining the gate trench, a metal gate electrode arranged in the gate trench on the gate dielectric, and an electrically insulating cap arranged on the metal gate electrode and within the gate trench.